CA2149752A1 - Liquid dispensing apparatus - Google Patents

Abstract

A dispensing apparatus (10) for dispensing metered quantities of a liquid. The apparatus comprises a peristaltic pump (11) having a pump inlet (13) adapted for connection to a liquid supply (17) and a pump outlet (15). Flow from the pump outlet (15) is controlled by a control valve (45) having a valve intake (47) for receiving liquid from the pump outlet and two valve outlets one being a return outlet (48) communicating with the pump inlet and the other being a discharge outlet (49) communicating with a dispensing handpiece (21). The control valve (45) has two modes of operation, one being a recirculating mode in which liquid entering the intake is directed to the return outlet and the other being a discharge mode in which liquid entering the valve intake is directed to the discharge outlet. A control means including a key pad (25) on the dispensing handpiece (21) is provided for controlling operation of the control valve in the two modes and for controlling operation of the pump.

Description

2 i 4 9 7 ~ ~ PCTJAU~U00~ ;

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The present invention relates to a liquid dispensing apparatus and relate~ particularly, though ~ot exclusively, to a drink d~spen~ing apparatus.

S ~ACK~ROUND TO THE INVENTION
Drink dispensing apparatus are known ~or dispensiny a drink by means of a pump into a glass or cup. In general, the volume of liquid dispensed is contro~led man~ally and relies on the user ascertaining visually when the required vol~me has been dispensed. The known apparatus do not permi~
a metered volume of liquid to be dispensed accurately and consistently.

SUMMARY OF THE I ~ ION
The present invent~on was developed with a view to - 15 providin~ a diæpensin~ apparatus which can dispense metered ; quantitles of liquid accurately.
~- Accordin~ to the present in~ention there is provided a llquid dispensing apparatus comprisin~:
a pump having a pump lnlet adapted for connection to a liquld -~upply, and a pump outlet;
a control valve having a valve intake for receivlng liquid from the pump outlet, and two val~e outlets one being ~ return outlet communlcatlng with the pump inlet and the other being a discharge outlet, said control valve h~ving two modes of operation, namely a recirculatlng mode in which liquid enter~ng the intake ls directed to the return outlet and a disGharge mode in which llquld entering the valve lntake is d~recte~ to the disch~rge outlet; and, a control means for controlling operation of the : 30 control valve ln said two des of operation and for controll~g operation of the pump whereby, ~n use, a controlled quanttty of liqutd can be dispensed from the discharge outlet of the control valve.

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0 94/124~,7 214 9 7 a 2 PCIIAV92/000 The colltrol means may i~corporate a time delay whereby the coIl~rol valve is caused to move f rom the rec~rculating mode into the dischasge mode a pred~termined time i~terval after commencement of o~eration of t:he pump. The 5 purpose of this is to allc~w the pump to develop liquid pressure at the pump outlet before operation o~ the control valve.
ConY~nie~tly, the pu~p comprises a peristaltlc pu~p havi~g a resiliently defon~able lic~uid transport line along which a movable member passes to ~rogressive~y de~orm the transpor~ line and propel the liquld through the line.
The dis~ensing apparatus may further comprise a dispe~sing l~ne~ one end of which commu~icates with the dischar~e outlet of the eontrol valve.
A dispens~ns handplece may be fitted to the o~her end of the dispsnsing llne.
The control means may include an actuating means i~corporated in the dispensin~ handpiece whereby operat~on of the pump and the co~trol me~ns can be ~nitiated frQm the handpiece.
: 20 The dispensing apparatus may be adapted to dispense variou~ types of liquid. For thls~purpose, the peristaltlc pump may ~ave a plurallty of such reslllen~ly deformable.liquid transport lines esch extending between a respectlve pump inlet and pump outlet J and a plurality of such control valves each associated with a respectlve one of the transport lines.

BRIEP DE~RIP~ION OF THE DRAWTNGS
The invention will be described with particular reference to drink dispens~ apparatus. however it is to be understood that it has wider appllcation to the dis~enslng of other liquids, ~or example, in the ~ood processing industry or medical field.- The nature of the invention will be better understood from the followin~ detailed description of specific embodlments thereof, given b~ way of example only, with reference to the accQmpanying drawings, in which:-Fig. 1 is a schematic view of one èmbodiment of a dl~pensing apparatus according to the invention;
Fi~. 2 ls a schematic elevatlonal view of a houslng ~0 ~2427 2 1 ~ 9 7 5 2 ~
..
_ 3 _ for a peristaltic pu~p f ormlrlg part o~ the dlspensing apparatus illustrated :L~ FiçJure l;
Fi~. 3 is a fragmentary view of the peristaltic pu~p of ~igure 2 illustrating a 3;)1urality of 'cransport tubes and a 5 rotor having rollers which pass in successlon over the transp~rt tubec;
Fig. 4 is a ~er8pective vi~w of an alternative ~bodime~t of the xotor:
Fig. 5 is a perspective view of ~ statlo~ary ~art of 10 l;he perist2l1t~c: pump includinçJ the transport tubes;
Fi~. 6 is a schematic view of a control valve, the control vAlve being shown in a recirculating mode;
Fig. 7 is a view simllar to Fig~ 6 except that the ~ontrol valve is show~ in a discharge mode; and ~ig. 8 is a schematic view of a reservoir which ls provided in the dis~ensing apparatus of Figure 1;
Fig. 9 is a schemat~c view of a second embodiment of a dispensing apparatus accor~n~ to the invention;
Fig. 10 is a schematic view of a third embodiment of a dispe~slng apparatus according to the invention;
~ ig. 11 is a schematlc vi~ Qf a fourth embodiment of a dispens~n~ appsr~tus accordlng to the invention;
Fig. 12 is an enlargement of a discharge nozzle employed ln the apparatus of Fig. 11.

~5 ~
Figures ~ to 8 illustrate a first embo~ment of a l~quid dispensing apparatus 10 for selectively dispensing drinks of various tyFes. In particular, the dlspensing apparatus 10 is adapted to ~ispense metered quantities of bottled alcoholic liquor.
The dispe~s~ng a~paratus 10 comprises a pump 11 illustrated mnst clearly in Figures 3, 4 and 5 having a plur~llty of pump inlets 13 and an equivalent number of pump outlets 15. Each ~ n let 1~ receives liquid from one of a plurality of bottles 17 unted ~n lnverted fashion on a rack 19. E ch outlet 15 communicates with a dispensing handpiece 21 on the ou~er end of a flexible condutt 23 as illus~rated in 21~ 9 7 S 2 PCrlAU921~3 Ft 5J. 1. The handpiece 21 incorporates a dis~e~slng nozzle 24 a~d an actuatir~ mean~ i~ the fonn of a key pad 25 havln~ a series of keys, one corresponding to each o~ the bottles 17.
With thiS arrangement, actuation of any one of the keys causes 5 the pump 11 to dellver a metered quantlty of alcohol~c beverage .from the correspondirlg bottle 17 to the dispe~si~g handpiece 21 from where i~ carl be d~spensed into a glass or other vessel.
As illustrated most cle~rly ~n Figures 3, 4 and 5 the pump 11 is .ln the form of a p~rista~tic pu~p having a 10 st~tionary part ~7 a~d a rotatable part 29. The stationar~r part 27 co~aprises a base 31 and a plurality of liquid transport lines 33 mounted on the base 31. The liquid trans~ort lines ~ 33 are each in the form of a length of resiliently cleformable tube one end of which defines a respective one o~ the plurality of pump inlets 13 and the other end of which defi~es a re~ective one of the plurality of pump outlets 15. The liquid transport tubes are typically manufactured from a hard-wearing, lo~g-l~f~ material, such as a latex based or synthetic plastics material of known composition. The liquid transport tubes 33 are sec~red to the base 31 by ~ecuring bra~ket 35.
The base 31 is provided with a con~ave depression 38 whlch acc~mmodates the rotor 29 and an $ntermediate portion of each of the llquld transport lines 33. The radius of curvature of the concave depression 38 corresponds to, and is slightly lar~er than, the radius o~ the circulaX path of movable members 37 on the rotor 29. The dlfference in the radi~ is ap~rQximately equal to the thlckness o~ the liquid transport tub~s 33 whe~ deformed to a fully fla~tened conditlon.
typically 2 to 4~m. The shap~ of the base 31 is desi~ned to ensure a proportio~al relationship between rotation angle of t~e rotor a~d volum~ of the displaced liquid.
The rotor 29 comprises a plurality of circumferentl~ly spaced longitudinal membexs 37 su~ported ~etween su~porting rotor discs 39. While not apparent from the drawingæ, the longitudinal members 37 are preferably in the form of rollers each of which can rotate about i~s central lo~gitud~nal axis on a shaft mounted between the discs 39. The rollers 37 on the rotor illustrated in Fig. 3 are coaxially 214~7~2 PCrIAU921006;23 ~....

_ 5 _ -moun~ed on cQmmon shafts (not illustrated) that ~ass throu~h all three discs 39. Fi~ure 4 illustrates a ~ore prefexred form of the rotor 29 in which each roller 37 is o~fset with respect to it's neighbour and is rotatably supported on it's own shaft between two of the discs 39. This is a more preferred arrangement as it reduces thP load on ~ motor driving the rotor, and al~o reduces the noise produced during operation of the ~eristaltic pump 11. The an~ular spacin~ o~ the rollers is selected so that a~ o~e roller 37 commences lts ~assa~e over the defo~mable transport tubes 33, ~he immediately preceding roller is still in contact with the transport tubes 33 as lllustrated, for example, in Fig. 2. Thls ensures that ~ peristaltic pressure is m~tai~ed in the tubes 33 between successive passes of the rolless 37.
lSA drive motor 41 drives the xotor by way of a belt and pulley transmission 43 as illustrated in Fig. 2.
Advantageously the belt and pulley tra~smission co~prises a timing belt ha~ing a pl~rallty of teeth provided thereon which - ~ eng~ge wlth the teeth on a palr of sproc~ets provided on the rotor drive shaft and motor shaft respectively. A sensing m~a~s, ty~ically in the fonm of a p~o~odetector 44, sensas the movement of the teeth of the tlmin~ belt and/or one of the sprock~t~ and generates an electrical signal ln the form of a pulse train i~dicative of the number of teeth passing the phot~detector 44. The number of teeth passing the photodetector 44 ls directly proportional to the volume of liguid being pu~ped through the tubes.
During operation of the pump. the longltudin~l members 37 pass successively along the intermediate portions o~ the. liquld transport lines 33 as the rotor rotates and progressively de~orm (~queeze) the intermediate portions so as to pump liquid from the inlets 13 to the outlets 15.
The dispensin~ apparatus has a plurality of contxol valves 45, one associated with each transport line 33. The control valves 45 each comprlse a sllding-spool 46 directional flow valve havln~ an lntake 47 connected to the respective pump outlet lS, and two outlets, one being a return outlet 48 and the other beln~ ~ discharge outlet 49. The return outlet 48 ~ ` 7 21~ 9 7 5 2 pcrlAu92lo~3 .~, is cor~nected to the re~pec~ivç~ pump inlet 13, a~d the dlscharsJe outlet 49 communicates with the dlspensing nozzle 24 of the dispensing handpiece 21 via a respectiv~ dispensing tube 51.
The return outlet 48 c~mmunicates with the respective pump 5 inlet 13 by way of a return line 50. Each control valve 45 has two modes of operation, one bein~ a recirculatin~ mode in which.llquid entering the intake 47 is directed to the return outlet ~8 and the other being a discharge mode in which li~uid enterin~ the valve intake 47 is directed to ~he d~scharge outlet ~9. Movement of the control val~e 47 between the recirculating mode and the discharge mode is e~fected by sliding of the valve spool 46 in conventional manner. Each - control valve 45 is typically a solenoid valve in which sliding movement of the valve spool 46 is effected by a solenoid actuated by an electrical signal. ~nd normally restlng in the recirculating de prior to actuation.
A control mean~ (not illustrated) is provided for controlling operation of each control valve 47 and the peristaltic pump 11. The control means comprises an electronic control circuit having an actuatin~ means deflned by the key pad 25 incorporated in the dispensing handpiece 21. The control circult incorporates a time delay whereby the control valve is caused to ve from the reclrculating mode (as shown in Fig. 7) into the discharge mode (as shown in Fi~. 6) a predetermined time i~terval. for example, 0.2 to 2.0 seconds, after commencement of operation of the pump. Typically, the time delay is approx~mately O.S seconds. The time delay allows the ~ump to operate and produce liquid pressure at the varlous pump outlets 15 prior to operation of the control valve. It al~o allows the tor 41 to develop full torque a~d attain a constant speed.
The control circuit may provide analogue signal processing, and typically also lnvolves d~gital slgnal process~ng to effect some of the control functions. A suitable programmable logic array (PLA) and/or a microprocessor based controller may be employed to effect the digital signal processing. The control circuit is responsive to actuation of - a key on the key pad 25 to activate the pump 11 and a 214~7~2 pcrlAug2loo~
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correspon in~ control valve 45. The photod~tector 44 provides a feedback s~ gnal to the control circu:Lt in the form of the pulse tr2~n which is ~ndicative o~ the volum~ of li~uid being pumped thxough the tube~. The co~trol circuit coullts the 5 pulse a~d compares the couslt wi~h a pr~set n~er. Each liqtLid transport line ha~ ~ uni~ue number, which may dif fer frcm line to line, re~lectlng th~ dlf~ere~c~ in the ~hystcal properties such ~s vlscoslty of the liquid~, displaced volume and pressure drop in a line. The ~reset n~mbar typically represents a predetermined standard volume of spirits, for example, 30ml, known i~ the liquor induætry as a "nip", or possibly l5ml, or a ~half nlp~. A$ soon as the number of pulses equals the preset number the control circuit deactivates the control v~lve which returns to the recirculatln~ mode.
The control valves 45 are rapid acting and can move fr~m the dischar~e mode to the recirculating mode and vice versa practically instantaneously. Hence the valve ca~
dispense a metered quantity of liquid accurately, typically to wlthin 0.05ml ~er lOml of splslts of a predetermined volume.
If desired, the oFerator ca~ obtain a double dose or double "nip~ of the æpirits by depressing th~ key on key pad 25 twice.
In this embodlment th~re are a plurality of dispensing lines 51 housed withi~ the flexible conduit 23, one .dlspensing line corresponding to each pump outlet 15. Each dispensing line 51 is coDnected at one end to the discharge outlet 49 of the res~ective co~trol valve 45. The other end of th~ dispensing line S1 open~ lnto the dispensing nozzle 24 of the dispensing handplece 21.
There are.a plurality of liquid reservoirs 61 housed in the rack 19, one corres~o~ding to each of the pump inlets 13. Each pump inls~ 13 communicat~s with a respective one of the reservo~rs 61 by way o~ a dellvery line 63 having an intake portion 64 opening into the reservoir ad~acent the bottom thereof. As illustrated in Fi~. 8 the top wall ~6 of the reservoir has an ~let 65 adapted to receive a sp~got 67 which is received i~ the mouth of a respective one of the inverted bottle~ 17 mounted on the rack. The spigot 67 has a spring loaded ball valve thereln, and as the spigot 67 ~s pushed down , ~~ ,,. .. . ~ . . . . . .

21~97~;~
WO g4n2427 PCrl~U92~00~3 into the l~e~ ~5 a pin forces th~ ba:Ll upwards, thu8 opening the valve and allowlng the l~quor to flow i~to the reservoir~
The contents of ~e bottle 17 progres~ivaly drairl into the reservoir as liquid is pu:mped from lt. A vent 70 is 5 incorporated in the reservoir to facilitate thls action. A
level ~en~;or i~clu~n5J a prob~ 71 is associated wlth the re~ervoir ~uch ~ t whe~ ~che liquid in the reservoir f alls belc)w a predete~ ed level, t~e pu~Lp can no longer be operated. T~e purposs of the reservo~r is to ensure that there ~s sufficlent liquid available for a metered quantlty of the liquid to be di~pensed o~ oper~tion of the pump. Th~ reservo~r also ensures a smooth liqu~d discharge from a bottle and eliminates ~he influence of a head pressure in the bottle.
Whe~ ~he l~quid level i~ the reservo~r ~alls below the predetermiaed level, the correspondin~ co~trol valve 45 is deactlvated and the e~pty bottle 17 must be removed and replaced with a full bottle.
The dispensing apparatus according to the embodiment allows a measured quantity o~ alcoholic liquor from any one of the bottles 17 to be dispensed at the handpiece 2~ simply by pre~æ~n~ the appro~riate key on theqkey ~ad 25. When one of th~ key~ on the key pad 25 is pressed, th~ motor 41 is actuated so as to cause the rotor 29 to rotate. As the rotor rotates, the rollers 37 succe~ively pass along the various transport line~ 33 a~d so transport llquid through the lines from the inlets 13 to the outlets 15 and thus develop liquid pressure at the outlets. After the predeterm$ned time interval, which is typically 0.5 seconds, the particular control valve gS
corresponding to the pxessed key is caused to move from the recirculating de into the discharge mode so allowing liquid to be delivered along the dispensing llne 5~ to the handpi~ce 21. Metering o~ tbe dispensed liquid is controlled by the control clrcuit as described above. The control valve is returned to the reclrculatin~ mode and rotation is terminated once the m~tered quantlty has been dispensed.
At the time whe~ the partlcular control valve is in the discharge ~ode. the other control valves remain in the recirculating mnde so that llquld transported along the 21~37~2 YCTlAUgU~

_ g _ transport li~es 33 as a result of rota~ion of the rotor is returned ~o the various pump inlets 13.
Figure 9 illustrates a second embodiment of the liquid dispensing ~ppar tus according to the invention. This embodiment o~ the liquid dispensing apparatus 10 is similar to that i~lustrated in Flgure 1 except tha~ the pump, electric motor and control valves are ~ow housed within the base 80 of the rack on which the inverted bottles are mounted. In th$s embodimen~ of the drink dispensi~g unit a single dispensing hand piece 21 on the outer end of a fixable conduit 23 is provided, simllar to that of Flgure 1. The construction and operation of the drink dis~ensing unit 10 illustrated in Figure 9 is otherwise subst~ntially identical to that of Figure 1 and will not be described again here. Obviously, the drink dispensing unit 10 can be designed to accommodate any number of bottles 17, eight bottles being a preferred number fxom the point of view of. the 8ize of the unit and the range of splrits generally offered at st bars.
Figure 10 illustrates a third embod~ment of the driDk dlspens~n~ unit 10 similar to that illustrated in Flgure 9, : except that two d~s~enæing hand piecês 21 sre provided on the outer end of resp~ctive flexible conduits 23. In general, only o~e hand piece can operate at a time for dispensing a metered quantity of drink. Typically, there is approximately a one second operational time to complete the discharge of the metered quantlty of drink, and during thi8 time the other hand piece is locked out. but can be activated immediately after discharge is completed with the first hand piece. Thls only ap~lies if both hand p~eces are ~eing used to dispense the~same l~quor, however lf different liquors are requlred then both hand pieces c~n be oFerated simultaneously. The unit may also be design4d to allow the use of two sets of discharge tubes operating from two sets of solenoid v~lves for each liquid ~ra~sport line, so that liquor from the same bottle can be dispens~d simultaneously wlth both hand pieces.
Pigure 11 illustrates a fourth embodiment of a drink ,: dispensing unit according to the invention, which is similar to the embo~m~nt of Plgure 10 except that the hand pieces have i 2149~5~
~ ~U~ PCTI~U~UW~3 been removed and the re~pective dispansiag lines co~nected to the dischar~e outlet~ 49 of the control v~lves communicate with specially deslgn~d outlet nozzles 90. The outlet nozzles 90 cQmpriEe a plagtic cone-sha~ed block, havlng a plurality of outlet apertures, ei~ht of which are connected to the di~Fensin~ lines 51. The other outlet apertures in the outle~
nozzle 90 may be conaected to an extarnal supply or supplies of soft drlnk, mixer~ or other liquids. Between the nozzle 90 and the eKternal supply or supplles, a set of external solenoid valves are provided, the external solenoid valves also bein~
connected to the control circult to regulate the supply of - external products on demand~ Advantageously, the outlet nozzle 90 is mounted about the discharge tube of an lce dispenser 92, the operation of which is 21so controlled by the control circuit of the drlnk dispensing unit 10. ~n this embodiment, actuating means in the form of key pads 94 are provided to enable a user to select a metered quantity of a desired l~quor, and/or an external supply of product or ice. The e}ectro~ic control circuit can ~e preprogrammed so ~hat by ~ressing a single key on key ~ad 94 the user can select a particular mixed drink, for example, ice, spirit~ and mixer in metered qu~ntitles.
Now th~t numexous embodiments of the liquld dispensing apparatus according to the invention have been descr1bed in detail. it will be apparent that the inventlon provides significant advantages over prior art liquld dispensing apparatus. The described drink dispensing lln~ t enables accurate and rapid dispensing of metered quant~ties of liquid. ~urthermore, the apparatus ensures a high degree of accura~y and repeatability regardless of variations and a~mos~heric pressure, head pressura represented by the level of a liquid in a bottle and reservoir. and physlcal properties o~ the liquid. The ~rovision of control means to control the o~eration of the control valves and pump sivefi the apparatu an inherent versatility 8S to the m~nner in which liquids are dispensed in metered quantlties. The control means can also be used to ~rovide stock control and may be provided with memory msans and adapted ~or connection to an external _, ., . . ~ .. .. . . . - . . . ~

~ 5u~2 2 1 4 9 7 ~ 2 PCTtAU~W~3 computer.
Numerous variations and modifications will suggest ~hemselves to parsons skllled in the relevant arts, in additlon to those already described, wlthout departin~ frGm the basic ' ~ inventive concepts. For example. althou~h each o~ the described embodiments employs a Feristaltlc pump, any sultabla pumpin~ system may be employed. A periætaltic pump i8 preferred as it provides a conve~ien~ ~ea~s of pump~n~ a pluxality of liqu~ds separately between a plurallty of pump inlets and Fespective pump outlets. Furthermore any suitable means for sensing the quantity of liquid displaced by the pump and providing a feedback si~nal to the control means o~ the ap~aratus ca~ be employed. For example. a liquid flow sensor may be incorporated in each of the discharga outlets of the control valves. All such variations and modifications are to be considered with~ n the ~cope of the present invention, the nature of which ls to be determ~ned from the foregoing description ~nd the appended claims.

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Claims (10)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-

1. A liquid dispensing apparatus comprising:
a pump having a pump inlet adapted for connection to a liquid supply and a pump outlet;
a control valve having a valve intake for receiving liquid from the pump outlet and two valve outlets one being a return outlet communicating with the pump inlet and the other being a discharge outlet, said control valve having two modes of operation, namely a recirculating mode in which liquid entering the intake is directed to the return outlet and a discharge mode in which liquid entering the valve intake is directed to the discharge outlet; and, a control means for controlling operation of the control valve in said two modes of operation and for controlling operation of the pump whereby, in use. a controlled quantity of liquid can be dispensed from the discharge outlet of the control valve.

2. A liquid dispensing apparatus as claimed in claim 1, wherein the control means incorporates a time delay whereby the control valve is caused to move from the recirculating mode into the discharge mode a predetermined time interval after commencement of operation of the pump.

3. A liquid dispensing apparatus as claimed in claim 2, further comprising sensing means for sensing the operation of said pump and for generating a feedback signal indicative of the quantity of liquid transported through the pump, said control means being responsive to said feedback signal to return the control valve to the recirculating mode when a metered quantity of liquid has been dispensed from the discharge outlet of the control valve.

4. A liquid dispensing apparatus as claimed in claim 1, wherein the pump comprises a peristaltic pump having a resiliently deformable liquid transport line and a movable member for progressively deforming the liquid transport line whereby the liquid is transported through the line.

5. A liquid dispensing apparatus as claimed in claim 4, wherein said liquid transport line is one of a plurality of such resiliently deformable liquid transport lines each extending between a respective pump inlet and pump outlet, and wherein said control valve is one of a corresponding plurality of such control valves each associated with a respective one of the liquid transport lines.

6. A liquid dispensing apparatus as claimed in claim 5, wherein said movable member is one of a plurality of rollers rotatably mounted on a motor driven rotor, and wherein as the rotor rotates the rollers successively roll over an intermediate position of each of said transport lines whereby said intermediate portion is progressively deformed to transport the liquid through the lines.

7. A liquid dispensing apparatus as claimed in claim 6.
further comprising a plurality of dispensing lines one end of each of which communicates with the discharge outlet of a respective one of the control valves, and wherein the other end of the or each dispensing line opens into a dispensing nozzle.

8. A liquid dispensing apparatus as claimed in claim 7, wherein the control means further comprises an actuating means whereby operation of the pump and the control means can be initiated manually by operating the actuating means.

9. A liquid dispensing apparatus as claimed in claim 1, wherein the liquid supply comprises a liquid reservoir connected to the pump inlet whereby a sufficient supply of liquid can be made available for a metered quantity of liquid to be dispensed on operation of the pump.

10. A liquid apparatus as claimed in claim 9, wherein the reservoir has a level sensing means whereby the control means can prevent operation of the control valve when the liquid level in the reservoir falls below a predetermined level.